When trading gold, you do not get real bullion, but speculate on the price of the underlying asset through spot price speculation, a futures contract or options. You can also trade CFDs on shares of gold mining companies and exchange-traded funds (ETFs).
Trading can allow you to make profits regardless of whether the price of the instrument goes up or down. While investing involves putting money into an asset that is expected to increase in value in the future, trading is about making a correct prediction about the direction of the asset's price.
If you have ever traded currencies on Forex, you will not find it difficult to trade gold, as the idea is the same. You deposit funds into the brokerage account and open and close positions, thus making profits or enduring losses. You can use a margin account and increase your initial deposit with leverage, which means you can start trading with just $100.